Caeleb Dressel staked his claim as the world’s greatest swimmer last year. He’s off to a pretty good start this year, too.

Dressel, who matched Michael Phelps‘ record with seven gold medals at the 2017 World Championships, shattered his own NCAA and American records in the 50-yard freestyle at the NCAA Championships on Thursday night.

The University of Florida senior became the first swimmer to break 18 seconds in the event, which is contested in a 25-yard pool rather than the 50-meter pool used for major international meets like the Olympics.

Dressel came into Thursday with the 11 fastest times ever, holding the NCAA and American record with an 18.20.

Then Dressel clocked 18.11 in Thursday morning’s preliminary session.

In the evening finals, he led off UF’s 200-yard free relay team with a 17.81, igniting a roar from the crowd at the University of Minnesota. About 50 minutes later, Dressel clocked 17.63 to win the individual 50 free, hitting his pre-meet goal time.

“There needs to be a fine line between goal setting and laughter,” said Dressel, who kneels, says a prayer and talks to himself before races to stay calm. “I don’t think you should sell yourself short. This meet, I think 17.6 was a perfect swim. There’s still room to improve. I think both of my breakouts were still pretty bad.”

In eight hours, Dressel chopped more than a half-second off the world record in the shortest race in swimming. He won the 50 free final by 1.01 seconds over Olympic 4x100m free relay teammate Ryan Held.

Before today, no person had ever swam the 50 free in under 18 seconds.

In comparison, the difference between NCAA women’s 50 free winner Simone Manuel and 11th place was .96.

Dressel is .84 faster than anyone else in history in this event (second place is 50m and 100m freestyle world-record holder Cesar Cielo of Brazil from his college days at Auburn), granted it’s not swum on the major international level.

Still, in comparison, the gap between the women’s 50-yard free record holder (Manuel) and the No. 63 woman on the all-time list is also .84, according to USA Swimming’s online records.

“I know probably everybody in the world of swimming expected 17.9, but I don’t really care about other people’s expectations,” Dressel said. “I want to set my own and put my own pressure on myself. I actually deleted all my social media, so I don’t know what people are saying. I don’t have a clue. It’s kind of nice actually, you guys should try it. I don’t have any apps on my phone. It’s very freeing.”

Dressel’s time drops in the last year have been astounding. At 2017 Worlds, he lowered his 100m free personal best from 47.91 (Rio Olympics) to 47.17. In the 100m butterfly, from 50.87 (2017 Nationals) to 49.86. In the 50m freestyle, from 21.53 (2017 Nationals) to 21.15.

“It’s not a shock. He’s incredible,” Lochte, who was in attendance in Minnesota, said on Thursday night, according to FloridaGators.com. “He is the next ‘you name it.’ He is the face of swimming from now on.”

Katie Ledecky capped her second NCAA Championships with a win by 28 seconds in the 1,650-yard freestyle on her 21st birthday Saturday.

It may have been her final college meet. Ledecky did not commit to returning for her junior season at Stanford, rather than turning pro, in a press conference after the Cardinal repeated as team champions in Columbus, Ohio.

“I have a final exam on Monday,” Ledecky said. “That’s about as far into the future I’m looking.”

Last year, Ledecky lapped all but one swimmer through 1,000 yards of the 1650 final and won by 21.19 seconds in 15:07.70.

On Saturday, Ledecky clocked 15:07.57. Her American record from earlier this season is 15:03.31 — 21.04 seconds faster than anybody else all-time.

Earlier this week, Ledecky anchored Stanford to an 800 freestyle relay title and won the 500 free by a record margin of more than eight seconds.

Then on Friday, teammate Ella Eastin beat Ledecky by 3.69 seconds in the 400 individual medley, an event that Ledecky never swims on the major international level. Eastin broke Ledecky’s NCAA record by 1.93 seconds.

“I think this is the best birthday party I’ll probably ever have,” Ledecky said on ESPNU. “It’s a long and grueling week. … This is the most fun I’ve ever had at a meet.”

Ledecky said she was “maybe a little off my goals” for the week. She did not break any of her American records in the convincing wins. Still, Ledecky finished the meet with eight NCAA titles in nine career NCAA Championships finals.

“I’m pretty hard on myself,” Ledecky said. “I set some pretty high goals. So if I fall a little short it’s not the end of the world. … I’m never really satisfied. If I was, I should retire.”

Also Saturday, quadruple Rio Olympic medalist Simone Manuel finished her Stanford career by winning the 100 freestyle in the second-fastest time ever — 45.65 and .09 off her American record.

Olympic and world champion Lilly King of Indiana broke her second American record of the meet, winning the 200 breast in 2:02.60 and lowering her mark by .58.

Cal’s Kathleen Baker, the Rio 100m back silver medalist, broke the 200-yard backstroke American record in winning in 1:47.30.

The NCAA Men’s Championships, featuring Caeleb Dressel and Joseph Schooling, are next week.

Katie Ledecky lost an NCAA Championships race for the first time in eight career finals, taking second in the 400-yard individual medley on Friday.

Stanford teammate Ella Eastin easily beat Ledecky by 3.69 seconds and grabbed the American and NCAA records from Ledecky, too. Eastin’s 3:54.60 is 1.93 seconds faster than Ledecky’s time from the Pac-12 Championships last month.

How did she do it?

“Honestly, I don’t know,” Eastin said on ESPNU. “I’ve built a lot of endurance this year, and it really showed.”

Eastin is decorated in her own right. She three-peated as NCAA 400-yard IM champion and held the American record in the event before Ledecky lowered it last month.

Eastin would have made the 2017 World Championships team had she not been disqualified for an illegal turn after finishing in second place at nationals.

Ledecky, a sophomore, has never contested the 400m IM at a U.S. Championships, Olympics or world championships, nor did she race the 400-yard IM at 2017 NCAAs. She raced the 400 IM instead of the 200 freestyle on Friday.

All of Ledecky’s races at major meets before Friday were in freestyle events. Her only defeat in a major international meet individual final was the 200m freestyle at 2017 Worlds.

Ledecky won five NCAA titles last year and the last two nights anchored the 800-yard freestyle relay and captured the 500-yard freestyle by eight seconds.

Later Friday, Lilly King of Indiana three-peated in the 100-yard breaststroke, breaking her American and NCAA records and winning in 56.25 seconds. King is also the Olympic and world champion in the 100m breast, plus the world-record holder.

“Always excited to get the record, but was really hoping to break 56 today,” King said.

Louisville’s Mallory Comerford became the second woman after Missy Franklin to break 1:40 in the 200-yard freestyle, winning in 1:39.80. Co-Olympic 100m free champ Simone Manuel of Stanford was third. Comerford and Ledecky tied for the 2017 NCAA 200 free title.

Stanford’s Ally Howe won the 100-yard backstroke in 49.70, one hundredth shy of her NCAA and American records. Olympic 100m backstroke silver medalist Kathleen Baker of Cal-Berkeley was third.

NCAAs conclude Saturday. Ledecky swims the 1,650-yard freestyle. She is the overwhelming favorite, having gone 35 seconds faster than anyone this season.

Ledecky hasn’t discussed with Stanford whether she will return for her junior season or turn pro, according to the school.